| 摘要 |
PURPOSE:To decrease the correlation of the carrier of two intermediate frequency(IF) signals and to eliminate the cancellation at the time IF synchronization by dislocating the relative phase of two-branched local oscillating lights. CONSTITUTION:An FSK signal light 1 transmitted by an optical fiber, after it is polarized and separated by a first polarization beam splitter 2, is made incident on a first multiplexer 6 and a second multiplexer 7 respectively. After the local oscillating light emitted from a local oscillating light source 3 is 2- branched to 1:1 by a branching device 4, one side is made incident on the first multiplexer 6 after it is delayed by a delaying fiber 5 of length 5m and other side is made incident on the second multiplexer 7 directly. The output of an IF synthesizing circuit 12 is inputted to a frequency discriminator 13, the control signal for IF stabilization is outputted, and inputted to the local oscillating light source 3. Thus, without depending on the polarization of the signal light 1, IF is stabilized to a constant value. |
